i was just testing my plugin with Reaper and the there available formats AU, VST and VST3. When I load the plugin as VST3 or AU, it receives an update on the new channel count after changing the channel count of the track it is loaded into. Not so with VST. Anyone knows if it is Reapers fault or something in the Juce code?

Some more information:
In <REAPER config directory>/reaper-fxoptions.ini you can see the settings (more or less cryptic) of your current plug-ins. If you are planning on using the canDo, you should delete your plug-ins out of that list, otherwise it won’t react to the changes (ignore the canDo as a matter of fact). Oh and don’t forget to upgrade to the lates Reaper version (well, at least 5.79 as Oli stated)